[Python-Dev] PEP 315 - do while

Hans Polak Hans.Polak at capgemini.com
Mon Oct 2 13:36:52 CEST 2006

Ok, I see your point. Really, I've read more about Python than worked with
it, so I'm out of my league here.

Can I combine your suggestion with mine and come up with the following:

          <setup code>
          <loop body>
          while <condition>
          <loop completion code>


-----Original Message-----
From: Nick Coghlan [mailto:ncoghlan at gmail.com] 
Sent: lunes, 02 de octubre de 2006 12:48
To: Hans Polak
Cc: python-dev at python.org
Subject: Re: [Python-Dev] PEP 315 - do while

Hans Polak wrote:
> Hi Nick,
> Yep, PEP 315. Sorry about that.
> Now, about your suggestion 
>      do:
>          <setup code>
>          while <condition>
>          <loop body>
>      else:
>          <loop completion code>
> This is pythonic, but not logical. The 'do' will execute at least once, so
> the else clause is not needed, nor is the <loop completion code>.  The
> body> should go before the while terminator.

This objection is based on a misunderstanding of what the else clause is for

in a Python loop. The else clause is only executed if the loop terminated 
naturally (the exit condition became false) rather than being explicitly 
terminated using a break statement.

This behaviour is most commonly useful when using a for loop to search
an iterable (breaking when the object is found, and using the else clause to

handle the 'not found' case), but it is also defined for while loops.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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